1. A solid-state laser diode comprising:
a laser diode for exciting a solid laser medium;
a constant current source for supplying a constant current to the laser diode;
voltage measurement unit for measuring a voltage at both ends of the laser diode; and
abnormality detection unit for detecting an abnormality at the laser diode based on an output of the voltage measurement unit.
2. A solid-state laser device comprising:
a plurality of laser diodes connected in series, for exciting a solid laser medium;
a constant current source for supplying a constant current to the laser diodes;
voltage measurement means for measuring the voltage at both ends of the laser diodes; and
abnormality detection unit for detecting an abnormality at the laser diodes based on the output of the voltage measurement unit.
3. The solid-state laser device according to claim 2, wherein the voltage measurement unit measures the voltage of the plurality of laser diodes individually to output the individual measured voltage to the abnormality detection unit.
4. The solid-state laser device according to claim 2, wherein when n (n is a natural number equal to or greater than four) laser diodes are connected, the voltage measurement unit measures the voltages of sets including m laser diodes (m is a natural number smaller than n) individually to output the voltages to abnormality detection unit.
5. The solid-state laser device according to claim 1, wherein a normal range having a finite width defined an upper limit value and a lower limit value as reference values of the voltage for determining abnormality of the laser diode is set; and
when the voltages at the laser diodes measured by the voltage measurement unit are equal to or higher than the upper limit value or equal to or lower than the lower limit value, the abnormality detection unit outputs an abnormality detection signal.
6. The solid-state laser device according to claim 5, further comprising:
reference value change unit for changing the normal range for the measured voltage set at the abnormality detection means on a basis of an input current value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A non-directional coupler having an operating frequency band, the coupler comprising:
a capacitor having a value greater than 10 picofarads; and
a semiconductor junction in series with the capacitor, the semiconductor junction having a threshold frequency below which the semiconductor junction behaves as a rectifier; wherein
the threshold frequency is less than the coupler’s operating frequency band; and
the coupler’s operating frequency band includes frequencies over one hundred MHz.
2. The coupler of claim 1, wherein the semiconductor junction is disposed in an epitaxial layer, wherein a thickness of the epitaxial layer determines the threshold frequency above which the semiconductor junction no longer functions as a rectifier.
3. The coupler of claim 1, wherein the semiconductor junction is sized to exhibit, at the coupler’s operating frequency within the coupler’s operating frequency band, a series capacitance of a few hundreds of femtofarads and a series resistance of a few tens of ohms.
4. An antenna circuit comprising:
an antenna;
a power amplifier configured to amplify a signal for the antenna, the power amplifier having an output that is configured to send the amplified signal to the antenna; and
a coupler interposed between the output of the power amplifier and the antenna, the non-directional coupler comprising:
a capacitor having a value greater than 10 picofarads;
a semiconductor junction in series with the capacitor, the semiconductor junction being formed to have a threshold frequency, the threshold frequency representing a frequency below which the semiconductor junction would behave as a rectifier; and
a coupler operating frequency band, the operating frequency band including frequencies over 100 MHz; wherein
the threshold frequency is smaller than the frequencies within the coupler operating frequency band such that the semiconductor junction does not behave as a rectifier at frequencies within the coupler operating frequency band.
5. The antenna circuit of claim 4, wherein the non-directional coupler is configured to extract data proportional to power transmitted to the antenna.
6. The antenna circuit of claim 5, further comprising a detector and a comparator, wherein the detector uses the extracted data to provide a measured value to the comparator, and wherein the comparator provides a control signal to the power amplifier.
7. A non-directional coupler having an operating frequency band of over 100 MHz, the coupler comprising:
a semiconductor junction in series with a capacitor, the capacitor having a value greater than 10 picofarads, and the semiconductor junction being formed so that the threshold frequency short of which the semiconductor junction behaves as a rectifier is smaller than the coupler’s operating frequency band of over 100 MHz.
8. The coupler of claim 7, wherein said semiconductor junction is formed in an epitaxial layer, the thickness of which conditions the threshold frequency.
9. The coupler of claim 7, wherein the semiconductor junction is sized to exhibit, at the coupler’s operating frequency band of over 100 MHz, a series capacitance on the order of a few hundreds of femtofarads and a series resistance on the order of a few tens of ohms.
10. A coupler comprising a semiconductor junction in series with a capacitor, the semiconductor junction being formed so that a threshold frequency of the semiconductor junction, short of which the semiconductor junction behaves as a rectifier, is smaller than the coupler’s operating frequency, wherein said capacitor has a value greater than 10 picofarads.